Coke is a solid carbon fuel and carbon source used to melt and reduce iron ore in the production of steel. In one process, known as the “Thompson Coking Process,” coke is produced by batch feeding pulverized coal to an oven that is sealed and heated to very high temperatures for 24 to 48 hours under closely-controlled atmospheric conditions. Coking ovens have been used for many years to covert coal into metallurgical coke. During the coking process, finely crushed coal is heated under controlled temperature conditions to devolatilize the coal and form a fused mass of coke having a predetermined porosity and strength. Because the production of coke is a batch process, multiple coke ovens are operated simultaneously.
Coal particles or a blend of coal particles are charged into hot ovens, and the coal is heated in the ovens in order to remove volatile matter (“VM”) from the resulting coke. Horizontal Heat Recovery (HHR) ovens operate under negative pressure and are typically constructed of refractory bricks and other materials, creating a substantially airtight environment. The negative pressure ovens draw in air from outside the oven to oxidize the coal's VM and to release the heat of combustion within the oven.
In some arrangements, air is introduced to the oven through damper ports or apertures in the oven sidewall, door, or crown to the region above the coal-bed (called the crown region). In the crown region the air combusts with the VM gases evolving from the pyrolysis of the coal. However, the buoyancy effect acting on the cold air entering the oven chamber can lead to coal burnout and loss in yield productivity. More specifically, the cold, dense air entering the oven falls towards the hot coal surface. Before the air can warm, rise, combust with volatile matter, and/or disperse and mix in the oven, it creates a burn loss on the coal surface. Accordingly, there exists a need to improve combustion efficiency in coke ovens.